Migraine typically begins with mild to moderate pain that increases in severity over several hours to reach peak severity. The painful phase of the migraine attack persists for 6 to 12 hours in most migraine patients. For those with migraines, the two most important features of migraine medications are providing quick relief and effectively decreasing pain. Migraine patients are dissatisfied with the amount of time to obtain pain relief after taking migraine medication. One group of very effective migraine pain relievers are triptans. The onset of relief or action of the triptans is measured by the rapid time to peak blood concentration (Tmax). Migraine patients reported relief of migraine related disability within 2 hours after dosing with a triptan. Migraine patients need rapid relief from their pain and desire a faster time to headache relief. (see Dawn A. Marcus, M.D., “Establishing a Standard of Speed for Assessing the Efficacy of the Serotonin1B/1D Agonists (Triptan)” Arch Neurol/Volume 58, June 2001 available on www.archneurol.com)
Naratriptan has been marketed under the trade name Amerge® by Glaxo Wellcome in the U.S. in tablets (2.5 mg) for oral administration. Naratriptan is a member of the drug class known as scrotonin (5HT) agonists and has been used as a pharmaceutical agent to successfully treats acute migraines. Naratriptan tablets are well absorbed, with about 70% oral bioavailability. Following administration of a 2.5 mg tablet orally, the peak concentrations are obtained in 2 to 3 hours. During a migraine attack, absorption was slower, with a Tmax of 3 to 4 hours.
Because migraine patients desire to return back to their daily task in life within a short time after taking migraine medication, there is a need to have rapid, complete relief of migraine pain within less than 2 hours after drug administration. So far, various efforts to improve the peak concentrations of Naratriptan have failed.